Flavoring and perfuming ingredients

ABSTRACT

Various compounds are disclosed to be useful in the flavoring of foodstuffs, animal feeds, beverages, pharmaceutical preparations and tobacco products. These compounds are equally useful perfuming ingredients.

This is a continuation, division, of application Ser. No. 451,423 filedMar. 15, 1974 now U.S. Pat. No. 3,927,030.

DESCRIPTION OF THE INVENTION

The compounds of the invention belong to the class of the derivativeslisted below:

A. 6-methyl-3-isopropyl-hepta-4,6-dien-1-ol,

B. 8-hydroxy-5-isopropyl-non-6-en-2-one,

C. 5-isopropyl-non-3-ene-2,8-diol,

D. 8-hydroxy-5-isopropyl-nonan-2-one, e. 5-isopropyl-nonane-2,8-diol,

F. 5-isopropyl-nonane-2,8-dione,

G. 3,4-epoxy-5-isopropyl-nonane-2,8-dione,

H. 8-hydroxy-5-isopropyl-8-methyl-non-6-en-2-one,

I. 6,7-epoxy-8-hydroxy-5-isopropyl-8-methyl-nonan-2-one,

J.2-isopropyl-5-methyl-6,8-dioxa-bicyclo[3.2.1.]octan-7-yl-methyl-ketone,

K.2-(2-isopropyl-5-methyl-6,8-dioxa-bicyclo[3.2.1.]octan-7-yl)-propan-2-ol,

L. 6-isopropyl-1,3,3-trimethyl-2,9-dioxa-bicyclo[3.3.1]nonan-4-ol, and

M.1-(2-isopropyl-5-methyl-6,8-dioxa-bicyclo[3.2.1]octan-7-yl)-ethan-1-ol.

These compounds, which are new, may be regarded as derivatives of5-isopropyl-8-methyl-nona-6,8-dien-2-one, better known under the name ofsolanone.

With the exception of 5-isopropyl-nonane-2,8-dione I have discovered thecompounds of the invention as compounds of natural origin which can beisolated from an essential oil. This essential oil can be obtained bysubjecting Burley tobacco to steam distillation, acidifying the aqueousdistillate to about pH 4, and extracting the acidified distillate with avolatile solvent.

However, the procedure for isolating the compounds from tobacco isextremely complex and completely uneconomical. The yield of essentialoil obtained is not higher than 0.03% by weight of the total tobaccotreated. Moreover, the compounds of the invention are very minorconstituents of the essential oil, having been detected therein at aconcentration varying from about 0.005 to about 0.3% by weight. In orderto isolate the desired compounds, the essential oil is subjected to apreliminary separation by fractional distillation under reducedpressure, and the less volatile fractions (b.p. above 35°C/0.001 Torr)are subjected to repeated fractional distillation using high resolutioncolumns. For the final isolation of the desired compounds, it has beenfound necessary to resort to repeated separations by preparative gaschromatography, using stationary phases of contrasting polarity.

The disadvantages and difficulties inherent in the isolation of thecited compounds from an essential oil obtained from tobacco have beenovercome by the realization of appropriate synthetic methods for theirpreparation. In this respect the specific procedures followed aredescribed in the examples given hereinafter.

Broadly, the compounds of the invention can be used for improving,enhancing or modifying the flavouring properties of foodstuffs, animalfeeds, beverages, pharmaceutical preparations and tobacco products, forimproving, enhancing or modifying the odoriferous properties of perfumesand perfumed products, and for the preparation of fragrant andflavouring compositions.

Thus, the invention provides a flavouring or perfuming compositioncomprising one of the compounds listed above.

The invention also provides a tobacco or tobacco substitute having addedthereto a small but flavouring effective amount of at least one of thecompounds listed above.

In their pure state, the compounds of the invention possess original andcharacteristic flavouring and perfuming notes. They can develop orenhance a variety of flavour or aroma notes, particularly the woody notereminiscent of the typical character presented by dry leaves, withanimal and sometimes fruity undertones.

These organoleptic characteristics make them particularly suitable forthe aromatization of infusions or decoctions, such as those made fromtea, camomile, lime or verbena.

A particular valuable feature of the pure compounds of the invention isthat their tenacious organoleptic characters are stable and perfectlyreproducible; whereas, in contradistinction, the properties of thenatural essential oil vary with the origin of the tobacco from which ithas been extracted, the method of extraction, and the purity of theessential oil recovered. Consequently, by virtue of their organolepticproperties, the compounds of the invention are useful as flavouring andperfuming ingredients over a wider field of applications than thenatural essential oil.

The compounds of the invention are particularly useful for theflavouring of tobacco. The tobacco used, for example, in the manufactureof cigarettes comprises a mixture of different types, blended to givethe desired characteristic flavour and aroma in the smoke produced.Thus, cigarettes currently manufactured usually contain mixtures ofVirginia, Maryland and Kentucky tobacco in combination with oriental orturkish tobacco. The proportion of each type of tobacco in the mixturecan be varied, in order to obtain the particular flavour and aromadesired. It is also common practice to employ flavouring agents andhumectants as additives in these tobacco mixtures, further to enhancetheir organoleptic properties.

It has now been discovered that the addition of one of the compounds ofthe invention to a tobacco base (which may be natural tobacco, or atobacco substitute of natural or synthetic origin) imparts thereto a dryleaf flavour, with woody, animal and sometimes fruity character. Theseproperties are particularly developed on smoking the tobacco. It hashowever to be pointed out that the characterization of the flavour andaroma of tobacco smoke is rather subjective and different smokers maydefine in a different way the organoleptic characteristics of the verysame tobacco.

The compounds of the invention can be used on their own, or incompositions comprising one or more flavouring or odoriferous compounds.The compounds and compositions of the invention may be used in a varietyof form, depending upon their chemical nature, solubility, but they arepreferably used in solution. For the flavouring of tobacco, they arepreferably added after ageing, curing and shredding, but before thetobacco is formed into cigarettes or other finished products. Aconvenient method for flavouring tobacco consists in spraying it with asolution of the flavouring compound or composition in alcohol, or in amixture of alcohol and propylene glycol.

For the perfumery, the compounds of the invention are particularlysuitable for developing herbacious type notes, specifically thosereminiscent of hay. More particularly, it has been found that by the useof2-(2-isopropyl-5-methyl-6,8-dioxa-bicyclo[3.2.1]octan-7-yl-propane-2-ol,8-hydroxy-5-isopropyl-non-6-en-2-one or8-hydroxy-5-isopropyl-8-methyl-non-6-en-2-one as perfuming agents it waspossible to develop herbacious type notes of particular interest.

The proportions in which the flavouring agents of the invention are usedin flavouring compositions or are added to tobacco can vary widely,depending upon the specific organoleptic effect it is desired to achieveand the type of tobacco to which they are added. Interesting flavouringeffects can be achieved with amounts ranging from 1 to 500 ppm,preferably from 10 to 200 ppm and most preferably from 10 to 50 ppm,based on the weight of the product flavoured.

Comparable proportions of the compounds of the invention can be used forthe flavouring of foodstuffs, beverages, animal feeds and pharmaceuticalpreparations.

When the compounds of the invention are used for the preparation ofartificial flavour compositions, they may typically constitute up to 80%by weight of the composition.

Similarly, when used as perfuming ingredient, the proportion of thecompounds of the invention in the perfume composition or perfumedproduct to which they are incorporated can vary over a wide range.Interesting odoriferous effects can be achieved with amounts rangingfrom 1 to 10% of the total weight of the composition.

In all cases, the range mentioned can be varied, in order to achievespecific odoriferous or flavouring effects.

The invention is better illustrated by the following examples, whereinthe temperatures are indicated in degrees centigrade and theabbreviations have the meaning common in the art. It has to beappreciated however that the invention is not deemed to be limited bythe given examples.

1. 6-Methyl-3-isopropyl-hepta-4,6-dien-1-ol

a. 17.2 g (0.2 M) of isovalerianic aldehyde were added under stirringduring 75 min. to a mixture of 28.4 g. (0.4 M) of pyrrolidine and 8 g ofanhydrous potassium carbonate. The temperature of the reaction mixturewaskept during the addition at 4°-6°, whereupon it was increasedto 20°while stirring and kept at this value during 75 min. The reactionmixture was filtered and the precipitate was washed with ether while theorganic clear filtrate by evaporation gave a residue which upondistillation under reduced pressure yielded 23 g (83%) of the enamine offormula ##SPC1##

B.p. 62-4°/10 Torr.

b. 5.0 g (71.5 mM) of methylvinylketone in 10 ml of anydrous ether wereadded during 45 min. to a solution kept under nitrogen of 9.0 g (65 mM)ofthe enamine prepared above in 50 ml of anhydrous ether. The reactionmixture was kept during 24 h at room temperature under nitrogenatmosphere, whereupon 1.95 ml of water and about 11.2 ml of a 6N aqueoussolution of hydrochloric acid were added thereto in such a way as toadjust the pH value to about 5-6. After 1 h of supplemental stirring atroom temperature the reaction mixture was extracted twice with ether,washed with a 1% aqueous solution of hydrochloric acid followed bywashingwith a 5% aqueous solution of sodium bicarbonate, and finallywith a NaCl saturated solution in water until neutrality. The extractfinally obtainedwas rapidly distilled at mild temperature to give 6.6 g(65%) of 5-oxo-2-isopropyl-2-hexanal; B.p. 47-9°/0.001 Torr.

Ir : 2730, 2900, 1715, 1360 cm⁻ ¹

Ms : m-18 = 138

nmr : 0.96 (6h); 2.07 (3h); 1.5-2.6 (6h); 9.55 (1h) δ ppm

c. 23.4 g (0.15 M) of the keto-aldehyde obtained as indicated above,15.4 g(0.24 M) of ethylene-glycol and 0.15 g of p-toluenesulfonic acidin 150 ml of benzene were brought to the boiling for 30 min. Thereaction mixture after the usual treatments of washing, drying andevaporation of the volatile components, was distilled under reducedpressure at 0.001 Torr. 21.2 g (70%) of the ketal of formula v,15/9

were obtained. The purity of this compound was found to be of the orderof 60-70% as revealed by vpc.

B.p. 60-1°/0.001 Torr.

Ir (film) : 1120, 1360, 1710 cm⁻ ¹,

Ms : m⁺ = 200;

nmr : 0.85 (3h, d, J=2.5 cps); 0.98 (3H, d, J= 2.5 cps); 1.2-1.8 (4H,m); 2.03 (3H, s); 2.46 (2H, t, J=6.5 cps); 3.80 (4H, m); 4.65 (1H, d,J=4.5 cps) δ ppm.

d. A solution of 21.2 g (0.084 M) of the ketal obtained in accordancewith the procedure described under letter c) and 52 g (0.256 M) ofM-chloroperbenzoic acid at 85% in 1 lt. of chloroform was left in thedarkat room temperature during 12 days. The reaction mixture was thenconcentrated in vacuum, whereupon ether was added thereto. Afterfiltration and washing of the clear filtrate with a 5% solution ofsodium carbonate, 18 g of the raw product were obtained. This compoundwas then dissolved in 100 ml of dioxan and 40 ml of 5% aqueous sulphuricacid. A solution was thus obtained which was then left 24 h at roomtemperature, whereupon sodium chloride was added and the productextracted twice with ether. The combined organic extracts were washedwith water until neutrality, dried over sodium sulphate and evaporatedto dryness to yield a residue which on fractional distillation gave 6.5g (23.8%) of a producthaving B.p. 50°-65°/0.001 Torr. This productcontained 53.6% of the ester-aldehyde of formula ##SPC2##

e. 5.5 g of a 14% solution of n-butyl-lithium in hexane were added in anitrogen atmosphere under stirring during 45 min. to a mixturecontaining 4.65 g. (13 mM) of methallyl-triphenylphosphonium chloride in40 ml of ether. The temperature of the reaction mixture was kept between6° and 10° during the whole addition and it was then increased toroomtemperature and kept at this value for 4 h. After cooling to -70°1.72 g (5.3 mM) of the esteraldehyde prepared according to paragraph (d)hereinabove in 5 ml of ether were added to the reaction mixture bytaking care that the temperature does not increase above -50°. Afterhaving been left at said temperature for 3 h and at 20° during onenight, the mixture was diluted with water and then extracted with ether,whereupon the combined organic extracts were subjected to the usualtreatments of washing and drying. The residue obtained on evaporation ofthe volatile components was then treated at reflux during 1 h with 50 mlof a 1N solution of potassium hydroxide in ethanol. By extraction withether followed by the usual treatments on the ether extracts, 1.5 g of aproduct were obtained. This product by purification by means of columnchromatography (30 g of silica gel; eluant; benzene) gave 0.58 g (65%)of 6-methyl-3-isopropyl-hepta-4,6-dien-1-ol the purity of which was ofca. 95%. B.p. ca. 60°/0.001 Torr.

d₄ ²⁰ = 0.8833; n_(D) ²⁰ = 1.4805

Ir : 3340, 3090, 1760, 1630, 1600, 1040, 960 and 870 cm⁻ ¹,

Uv : λ_(max) ^(EtOh) = 230 nm (ε = 24,195)

Sm : m⁺ = 168

nmr : 0.80 (3h); 0.91 (3h); 1.80 (3h, s); 1.2-2.4 (4H); 3.47 (2H); 3.80(1H); 4.81 (2H); 5.33 (1H); 6.05 (1H) δ ppm.

2. 8-Hydroxy-5-isopropyl-non-6-en-2-one

6.51 g (17.8 mM) of the ketal of formula ##SPC3##

were added under vigorous stirring to a suspension kept at 20°-25° of0.455 g (12 mM) of lithiumaluminiumhydride in 30 ml ether. After 4 h ofsupplemental stirring the excess of lithiumaluminiumhydride wasdecomposed with moist ether, whereupon the reaction mixture was pouredonto a concentrated solution of ammonium chloride. After the usualtreatments 6.5 g of a product were obtained. This product was thentreated at 20° under nitrogen atmosphere with50 ml of a 5% aqueoussolution of sulphuric acid in 50 ml of ether. The separated organicphase was evaporated to give 5 g of a residue which on purification bycolumn chromatography (100 g of silica gel; eluant: a mixture of benzeneand ethyl acetate, the concentration of which varies inbetween 95:5 and3:2) yielded 3.4 g (96%) of 8-hydroxy-5-isopropyl- non-6-en-2-one; B.p.80°/0.001 Torr;

d₄ ²⁰ = 0.9261; n_(D) ²⁰ = 1.4608

Ir : 3450, 1710, 1360, 1050 and 975 cm ⁻ ¹ ;

Ms : m-18 = 180;

nmr (cdc1₃) : 0.87 (6h); 1.26 (3h); 1.0-2.0 (5h); 2.13 (3h); 2.40 (2h);4.30 (1h); 5.45 (2h) δ ppm.

The ketal used as starting material for the preparation given above canbe synthetized as follows:

a. 10.1 g (64.7 mM) of 5-oxo-2-isopropyl-2-hexanal (prepared accordingto paragraph b) of the above given example) were refluxed during 4 daysundernitrogen atmosphere with 22.2 g (69.7 mM) of the yield obtained bythe reaction between triphenylphosphine and chloracetone in 75 ml ofanhydrousbenzene (see: J. Org. Chem. 22, 44 (1957)).

The reaction mixture was then concentrated to dryness and the obtainedresidue taken up with about 200 ml of petrol ether (B.p. 30°-50°) andthe precipitate separated by filtration. On evaporation of the clearfiltrate followed by fractional distillation of the obtained residue,10.9 g of 5-isopropyl-non-3-en-2,8-diene were obtained; B.p.70°-84°/0.001 Torr.

b. A mixture of 5-isopropyl-non-3-en-2,8-dione (7.0 g; 35.7 mM), 0.040 gofp-toluenesulfonic acid, 2,46 g of ethylene-glycol in 40 ml of benzenewas refluxed in a Dean & Stark type separator during 11/2 h. Thereaction mixture was then washed with a 5% aqueous solution of sodiumbicarbonate, then with water before being subjected to the usualtreatments of extraction with ether, washing and drying of the organicextracts. On evaporation of the organic phase, 7.72 g of the desiredmonoketal were obtained. This product showed a purity of about 60-70%;

B.p. 87°-90°/0.001 Torr.

Ir : 1675, 1620, 1360 and 980 cm⁻ ¹ ;

Nmr (ccl₄) : 0.88 (6H); 1.19 (3H); 2.15 (3H); 1.0-2.2 (6H); 3.80(4H);5.87 (1H); 6.46 (1H) δ ppm

3. 5-Isopropyl-non-3-ene-2,8-diol

2.5 g of 5-isopropyl-non-3-ene-2,8-dione, prepared in accordance withthe method described in paragraph a) of the previous example, in 10 mlof anhydrous ether were added to a mixture of 0.292 g (7.7 mM) oflithiumaluminiumhydride in 10 ml of ether and 10 ml of tetrahydrofuran.The reaction mixture was left under stirring at 20° overnight, thenitwas poured onto a concentrated aqueous solution of ammonium chloride,extracted and treated as usual. The obtained residue was purified bycolumn chromatography (50 g of silica gel; eluant: ether/petrol ether)to yield the desired diol (1.3 g: yield 51%); B.p. 102°/0.001 Torr;n_(D) ²⁰ = 1.4645; d₄ ²⁰ = 0.9275;

Ir : 3350, 1120, 1060 and 970 cm⁻ ¹ ;

Nmr (cc1₄) : 0.67 (1h, s); 0.75-1.00 (6H, m); 1.16 (6H, t apparent,J=7.5 cps); 1.0-2.5 (6H, m) 2.8-4.5 (3H, very broad s); 5.37 (2H, m) δppm.

4. 8-Hydroxy-5-isopropyl-nonan-2-one

A mixture of 1.74 g (8.7 mM) of 5-isopropyl-nonane-2,8-dione, which canbe prepared according to the method described in example sixhereinafter, 0.545 g (8.7 mM) of ethylene-glycol, 0.020 ofp-toluenesulfonic acid in 20ml of benzene was refluxed during 11/2 h ina Dean & Stark type separator. The usual treatments of extraction withether, washing, drying and evaporation afforded 2.2 g of a mixturemainly containing a monoketal of formula ##SPC4##

This mixture was then reduced by means of 0.175 g (4.6 mM) oflithiumaluminiumhydride in ether at 20° during 20 h. After the usualtreatments of decomposition of the excess of lithiumaluminiumhydridethereaction mixture was treated with 6 ml of a 5% aqueous sulphuric acid in20 ml of dioxan. By extraction with ether followed by washing, dryingand evaporation of the combined extracts there was obtained a residue (2g) which on purification by column chromatography (40 g of silica gel;eluant: a mixture of benzene and ethyl acetate 95:5) gave 0.60 g (34%)of 8-hydroxy-5-isopropylnonan-2-one; B.p. 90°/0.001 Torr;

C₄ ²⁰ = 0.9368; n_(D) ²⁰ = 1.4589

Ir: 3450, 1705, 1360 cm⁻ ¹

Nmr (cdcl₃): 0.84 (6H, d, J=6 cps); 1.19 (3H, d, J=6 cps); 0.9-1.9 (9H,m); 2.15 (3H, s); 2.44 (2H, t, J=8 cps); 3.78 (1H, m) δ ppm.

5. 5-Isopropyl-nonane-2,8-diol

2.5 g (12.6 mM) of 5-isopropyl-nonane-2,8-dione, which can be preparedaccording to the process described in example 6 hereinafter, in 10 ml ofanhydrous ether were added to a mixture of 0.570 g (50 mM) oflithiumaluminiumhydride in 10 ml of ether and 10 ml of tetrahydrofuran.The reaction mixture was kept under stirring overnight at 20° and pouredthen onto a saturated aqueous solution of ammonium chloride. After theusual treatments of extraction, washing and drying followed byevaporation of the volatile portions there was obtained a residue whichonfractional distillation gave 2.3 g (90%) of the desired diol; B.p.120°/0.001 Torr;

d₄ ²⁰ = 0.9388; n_(D) ²⁰ = 1.4631

Ir: 3370 and 1120 cm⁻ ¹ ;

Nmr (ccl₄): 0.85 (6H, d, J=6 cps); 1.13 (6H, d, J=6 cps); 1.0-2.2 (10H,m); 3.3-4.5 (4H, m) δ ppm

6. 5-isopropyl-nonane-2,8-dione

1.96 g (10 mM) of 5-isopropyl-non-3-ene-2,8-dione, prepared according tothe method described in paragraph (a) of example 2, in 20 ml of ethylacetate were reduced by catalytic hydrogenation in the presence of 0.196gof palladium at 10% over charcoal. After filtration and evaporation ofthe volatile portions, a residue was obtained which by fractionaldistillationgave 1.77 g (89%), of the desired dione; B.p. 80°/0.001Torr;

d₄ ²⁰ = 0.9292; n_(D) ²⁰ = 1.4501

Ir: 1710 and 1360 cm⁻ ¹ ;

Ms: m-18 = 180;

nmr (ccl₄): 0.85 (6H, d, J=6 cps); 1.0-1.9 (6H, m); 2.05 (6H, s);2.37(4H, t, J=7 cps) δ ppm.

7. 3,4-Epoxy-5-isopropyl-nonane-2,8-dione

A solution of 16.25 g (ca. 40 mM) of the keto-ketal prepared inaccordance with the procedure described in example 2, in 125 ml ofanhydrous ether was added during 50 min. at room temperature to amixture of 1.14 g (30 mM) of lithiumaluminiumhydride in 75 ml ofanhydrous ether. The reaction mixture was then stirred during 4 h andsubsequently the excess of lithiumaluminiumhydride was decomposed withmoist ether, whereupon the mixture was poured into a concentratedaqueous solution of ammonium chloride. By the usual treatments ofextraction with ether, washing, drying and evaporation of the organicextracts, 16 g of a product were obtained, the analytical data of whichwere the following:

Ir: 3450, 1050, 965 cm⁻ ¹ ;

Ms: m-15 = 227;

nmr (ccl₄): 0.85 (6H, m); 1.17 (3H, d, J=6 cps); 1.18 (3H, s);1.0-2.3(6H, m); 3.78 (4H, s); 3.9-4.5 (2H, m); 5.2-5.5 (2H, m) δ ppm

The product thus obtained was dissolved in 20.4 g (100 mM) ofm-chloroperoxybenzoic acid at 85% in 380 ml of chloroform. After havingbeen left 24 h at 20°, the reaction mixture was evaporated to drynessunder reduced pressure and the residue was taken up with petrol ether(B.p. 30°-50°), and the organic phase washed with a 5%aqueous solutionof sodium carbonate followed by a concentrated aqueous solution ofsodium chloride.

After the usual treatments, there was obtained the3,4-epoxy-5-isopropyl-2-hydroxy-nonan-8-one ketal (18 g). This productwastreated with 160 g of MnO₂, previously activated during 20 h at 120°,in 1.4 l of benzene in nitrogen atmosphere. After 2 days of stirring at20°, the mixture was filtered and the clear filtrate evaporated todryness. There was thus obtained a residue which was then treated with2% aqueous sulphuric acid in a mixture of ether and dioxan (1:1:1). Thismixture was extracted with ether and the organic extracts were subjectedto the usual treatments to give 11 g of3,4-epoxy-5-isopropyl-nonane-2,8-dione which on purification by means ofcolumn chromatography (silica gel; eluant; petrol ether:ether 9:1 to1:1) gave the desired diketo-epoxide in its pure state.

B.p. 90°/0.001 Torr; d₄ ²⁰ = 1.0105; n_(D) ²⁰ = 1.4594

Ir (ccl₄): 1700, 1355, 1240, 1160 and 860 cm⁻ ¹

Ms: m-43 = 169;

nmr (cdcl₃): 0.95 (6H, 2d); 1.11-2.00 (4H, m); 2.09 (3H, s); 2.18(3H,s); 2.65 (2H, t, J=7.5 cps); 2.85 (1H, d of d, J=8.5 cps, J'=ca. 2cps); 3.19 (1H, d, J=ca. 2 cps) δ ppm

8. 8-Hydroxy-5-isopropyl-8-methyl-non-6-ene-2-one

7.2 g (18 mM) of the monoketal prepared in accordance with the proceduredescribed in example 2, in 20 ml of ether were added to a mixture of1.09 (45 mM) of magnesium turnings, 60 ml of anhydrous ether and anexcess of methyl bromide according to the usual technique applied forthe Grignard type reactions. The reaction mixture was then refluxed for1 h and left atroom temperature overnight, whereupon it was poured intoan icy 5% aqueous solution of sulphuric acid. After having been left atroom temperature for21/2 h more, the organic phase was separated andsubjected to the usual treatments of washing with a 5% aqueous solutionof sodium carbonate followed by a further washing with water. Afterdrying and evaporation, 7 g of a raw material were obtained which bypurification by means of columnchromatography gave 3.06 g (44%) of thedesired product.

B.p. 85°/0.001 Torr; d₄ ²⁰ = 1.4600

Ir: 3450, 1700, 1360, 1150 and 970 cm⁻ ¹ ;

Ms: m-18 = 194;

nmr (ccl₄): 0.85 (6H, 2d); 1.22 (6H, s); 2.03 (3H, s); 1.1-2.0 (4H, m);2.1-2.5 (3H, m); 5.23-5.50 (2H, m) δ ppm.

9. 6,7-Epoxy-8-hydroxy-5-isopropyl-8-methyl-nonan-2-one

2.96 g of 8-hydroxy-5-isopropyl-8-methyl-non-6-en-2-one (13.9 mM) weretreated with 3.4 g (16.7 mM) of m-chloroperoxybenzoic acid at 85% in 90mlof chloroform. The reaction mixture was kept during 72 h at 20°whereupon it was concentrated at low temperature and the obtainedresidue taken up with petrol ether. After filtration, the clear filtratewas subjected to the usual treatments to give 3 g of the desired rawepoxy-ketone. By purifying this compound by means of columnchromatography, 2.51 g of a pure compound were obtained.

B.p. 100°/0.001 Torr; d₄ ²⁰ = 9.9905; n_(D) ²⁰ = 1.4572

Ir: 3400, 1360, 1705, 1165, 960 and 900 cm⁻ ¹ ;

Ms: m-59 = 169;

nmr (cdcl₃): 0.96 (3H, d, J=6 cps); 1.23 (3H, s); 1.27 (3H, s); 2.13(3H, s); 1.15-2.10 (5H, m); 2.3-3.0 (4H, m) δ ppm.

10.2-Isopropyl-5-methyl-6,8-dioxa-bicyclo[3.2.1]octan-7-yl-methyl-ketone

0.50 g (2.38 mM) of 3,4-epoxy-5-isopropyl-nonane-2.8-dione preparedaccording to the process described in example 7, in 10 ml of benzenewere refluxed in the presence of 0.020 g of p-toluenesulfonic acidduring 4 h. After a supplemental addition of 0.020 g ofp-toluenesulfonic acid the reaction mixture was refluxed for 3 h more.By extraction with ether followed by the usual treatments of theseparated organic extracts, 0.315 g (63%) of the desired ketal wereobtained.

B.p. 80°/0.001 Torr; n_(D) ²⁰ = 1.4608 d₄ ²⁰ = 1.0324

Ir (ccl₄): 1700 and 1375 cm⁻ ¹ ;

Ms: m-43 = 169;

nmr (cdcl₃): 1.00 (6H, m); 1.58 (3H, s); 1.0-2.0 (6H, m); 2.25 (3H, s);4.24 (1H, s); 4.55 (1H, m) δ ppm.

The product is under the form of a mixture of its two stereoisomers offormula ##SPC5##

11.2-(2-Isopropyl-5-methyl-6,8-dioxa-bicyclo[3.2.1]octan-7-yl)-propan-2-ol(A)and 6-isopropyl-1,3,3-trimethyl-2,9-dioxa-bicyclo[3.3.1]nonan-4-ol (B)

2.1 g (9.2 mM) of the epoxy-ketol prepared according to the proceduredescribed in example 9, in 45 ml of benzene were refluxed with 0.045 gof p-toluenesulfonic acid during 2 h according to the conditions used inthe course of the preparation described in example 10 hereinabove. 2.2 gof a raw material were thus obtained which on purification by columnchromatography (silica gel; eluant: petrol ether: ether 4:1) gave 1.2 gofa mixture of 2 hydroxy-ketals. These latter can be separated by vpc(CARBOWAX ^(R) 5%; 200°; 2.5 m). ##SPC6##

Ir (ccl₄): 3500, 1030 cm⁻ ¹ ;

Ms: m-59 = 169;

nmr (cdcl₃): 1.00 (6H, d, J=6 cps); 1.22 (3H, s); 1.38 (3H, s); 1.46(3H, s); 2.13 (1H, s); 1.1-2.3 (6H, m); 3.78 (1H, d, J=4 cps); 4.28 (1H,d, J=ca. 4 cps) δ ppm ##SPC7##

Ir: 3500 and 1025 cm⁻ ¹ ;

Ms: m-43 = 185;

nmr (cdcl₃): 0.98 (6H, t apparent, J=5.5 cps); 1.27 (3H, s); 1.33(3H,s); 1.46 (3H, s); 1.1-1.8 (6H, m); 2.05 (1H, d, J=7 cps); 3.55 (1H,d of d,J=7 cps, J'=3 cps); 4.04 (1H, broad s) δ ppm.

2-(2-Isopropyl-5-methyl-6,8-dioxa-bicyclo[3.2.1]octan-7-yl)-propan-2-olprepared hereinabove occurs under the form of a mixture of stereoisomersof formula ##SPC8##

These latter correspond to the product as directly isolated from theessential oil of Burley tobacco.

By means of a separate synthesis it has been possible to prepare themixture of the isomers defined by the following formula ##SPC9##

as follows:

A solution of methylmagnesium bromide was prepared according to theusual technique of the Grignard type reactions by treating 0.109 g (4.5mM) of magnesium metal with 10 ml of an ether solution containing 0.475g (5 mM) of methyl bromide. To this solution 0.850 g (4 mM) of the ketalprepared according to example 10, dissolved in 5 ml of anhydrous ether,were added,whereupon the mixture was refluxed during 1 h and decomposedthen with a saturated aqueous solution of ammonium chloride. After theusual treatments of extaction with ether, washing, evaporation andpurification of the obtained residue by column chromatography (17 g ofsilica gel; eluant: petrol ether:ether 9:1) there was obtained a mixtureof two stereoisomers which could then be separated by preparative vpc(CARBOWAX ^(R) 5%; 200°; 2.5 m).

Isomer I:

Ir: 3500, 1020 and 845 cm⁻ ¹ ;

Nmr (cdcl₃): 1.00 (6H, t apparent, J=6 cps); 1.19 (6H, s); 1.44 (3H, s);1.3-2.1 (6H, m); 2.06 (1H, s); 3.78 (1H, s); 4.43 (1H, broad s) δ ppm

Isomer II:

Ir: 3500, 1020 and 855 cm⁻ ¹ ;

Nmr (cdcl₃): 0.93 (6H, t complex band); 1.17 (6H, s); 1.46 (3H, s);1.0-1.9 (6H, m); 2.10 (1H, s); 3.80 (1H, s); 4.38 (1H, broad s) δ ppm.

12.1-(2-Isopropyl-5-methyl-6,8-dioxa-bicyclo[3.2.1]octan-7-yl)-ethan-1-ol

0.1 g (0.47 mM) of the keto-ketal, prepared according to example 10hereinabove, in 3 ml of methanol was reduced by means of 0.01 g ofsodium borohydride. The reaction mixture was then concentrated underreduced pressure and the obtained residue taken up with a 10% aqueoussolution of hydrochloric acid, extracted with ether, washed with anaqueous solution of sodium bicarbonate (5%) and finally with water untilneutrality. The usual treatments gave the desired product under the formof a mixture of stereoisomers which could be characterized as follows:

Isomer I:

Nmr: 1.00 (6h, 2d); 1.15 (3H, d, J=6 cps); 1.44 (3H, s); 1.3-2.2 (6H,m); 2.51 (1H, broad s); 3.53-3.84 (2H, m); 4.29 (1H, broad s) δ ppm.

Isomer II:

Nmr: 0.95 (6h, m); 1.20 (3H, d, J=6 cps); 1.44 (3H, s); 1.0-2.0 (7H, m);3.55-3.95 (2H, m); 4.49 (1H, broad s) δ ppm.

Isomer III:

Nmr: 0.95 (6h, m); 1.15 (3H, d, J=6 cps); 1.46 (3H, s); 1.0-2.0 (6H, m);2.60 (1H, broad s); 3.44-3.85 (2H, m); 4.25 (1H, broad s) δ ppm

These isomers may be represented by the following formula ##SPC10##

13. Aromatization of tobacco

10 g of a American blend tobacco mixture were sprayed with 0.5 g of a 1°/oo solution of 8-hydroxy-5-isopropyl-non-6-en-2-one in 95% ethanol, andthe tobacco thus flavoured was used to manufacture "test" cigarettes. Asa control, cigarettes were also manufactured from the same tobaccomixture, sprayed with 95% ethanol alone. The smoke from the cigaretteswas subjected to organoleptic evaluation by a panel of flavour experts,who unanimously stated that the smoke of the flavouredcigarettespossessed a characteristic woody note, particularlyinteresting for the reconstitution of the "cigar" aroma. Other sampleswere equally evaluated in accordance with the same procedure and byusing the same proportions. The following table gives a list of theproducts thus evaluated together with the mention of the developedflavour.

                  TABLE                                                           ______________________________________                                        Compound  organoleptic evaluation.sup.(1)                                     ______________________________________                                        a         woody                                                               b         see example 13                                                      c         powerful, tobacco character, reminiscent                                      of the note of cigar                                                d         woody, dry                                                          e         woody, animal                                                       f         woody, animal                                                       g         slightly fruity                                                     h         woody, dry, tobacco character                                       i         tobacco notes of Virginia type                                      j         hay note                                                            k         woody, green                                                        l         burnt, animal                                                       m         woody                                                               ______________________________________                                         .sup.(1) The organoleptic characters mentioned refer to the properties of     the tested compounds on tobacco relative to the same tobacco unflavored. 

14. Perfume composition of the type "Classic Eau de Cologne"

A base perfume composition of "Classic Eau de Cologne" type was preparedbyadmixing the following ingredients (parts by weight):

    ______________________________________                                        Lemon oil             250                                                     Bergamot artificial oil                                                                             250                                                     Sweet orange oil      100                                                     Petitgrain bigarade   100                                                     Lavender               90                                                     Neroli bigarade        10                                                     Muscone 10 %*         100                                                     Total                 900                                                     ______________________________________                                        *in 95 % ethanol                                                          

By adding to 90 parts by weight of the above given base perfumecomposition10 parts by weight of 8-hydroxy-5-isopropyl-non-6-en-2-one, anovel composition was obtained. This composition possessed an enhancedodour of witch hazel type with a pleasant character of hay.

By substituting in the above example8-hydroxy-5-isopropyl-8-methyl-non-6-en-2-one or2-(2-isopropyl-5-methyl-6,8-dioxa-bicyclo[3.2.1]octan-7-yl)-propan- 2-olfor 8-hydroxy-5-isopropyl-non-6-en-2-one, similar effects were observed.

What I claim is:
 1. 6-Methyl-3-isopropyl-hepta-4,6-dien-1-ol having apurity of about 95%.
 2. A composition of matter consisting essentiallyof 6-methyl-3-isopropyl-hepta-4,6-dien-1-ol.